I have a question about Own height factor of large opening in TRNFlow: Our windows are normal casement window. Should it be 1? I think the opening is in a vertical wall. Is it right or not?
When replying, please edit your Subject line so it is more specific than "Re: Contents of TRNSYS-users digest..."
Today's Topics:
1. Re: heat exchangere (David BRADLEY) 2. Re: Strange error when using the equation proforma (David BRADLEY) 3. Re: Strange error when using the equation proforma (David BRADLEY)
4. Re: About building loads calculation in TRNSYS (David BRADLEY)
---------- 已转发邮件 ---------- From: David BRADLEY <d.bradley@tess-inc.com> To: trnsys-users@cae.wisc.edu
Date: Tue, 14 Dec 2010 15:56:15 -0600 Subject: Re: [TRNSYS-users] heat exchangere Elly, If you have the TESS HVAC library, there are a number of heat exchangers with controlled outlet temperature models in there. If not then you will need to use a variable speed pump (Type3) , the heat exchanger, and (most likely) a PID controller (Type23).
Best, David
I'm simulating, with trnsys 16, a plate heat exchanger for district heating
substation. I'm using type 5b, is it correct? There's a control unit that in function of external temperature and the hot- side outlet temperature (secondary pipe) open or close (%) the valve in the hot-
side inlet temperature (primary pipe). Can someone tell me how can i model a control unit? which types can i use?
-- *************************** David BRADLEY Principal Thermal Energy Systems Specialists, LLC 22 North Carroll Street - suite 370 Madison, WI 53703 USA
---------- 已转发邮件 ---------- From: David BRADLEY <d.bradley@tess-inc.com> To: a8304506@graduate.hku.hk
Date: Tue, 14 Dec 2010 16:00:22 -0600 Subject: Re: [TRNSYS-users] Strange error when using the equation proforma
Chun Kwong, You are correct in your understanding of how TRNSYS iterates to solve. However, it has to have somewhere to start so TRNSYS performs a check on all the equations before starting the simulation to make sure that it can solve them. If you wrote a set of equations that said:
EQUATIONS 2 A = B B = A
there would be no way that TRNSYS could ever solve because it would have nowhere to begin the iteration. My guess is that your T_CHWS and T_CHWR equations are too interdependent.
Best, david
Hello, everyone.
I am trying to simulate a chiller plant with primary and secondary chilled water
pump systems. I use to equation proforma to calculate the chilled water flow
and temperature at the supply and return header. However, I get the following
error messages:
*** Fatal Error at time : 0.000000
Generated by Unit : Not applicable or not available
Generated by Type : Not applicable or not available
TRNSYS Message 420 : The following variable defined in an EQUATIONs or
CONSTANTs card could not be solved as this variable depends on either an
undefined EQUATION or CONSTANT name or depends on another EQUATION or CONSTANT
that cannot be solved. For example A=B and B=A would trigger this error
Reported information : T_CHWS
*** Fatal Error at time : 0.000000
Generated by Unit : Not applicable or not available
Generated by Type : Not applicable or not available
TRNSYS Message 420 : The following variable defined in an EQUATIONs or
CONSTANTs card could not be solved as this variable depends on either an
undefined EQUATION or CONSTANT name or depends on another EQUATION or CONSTANT
that cannot be solved. For example A=B and B=A would trigger this error
Reported information : T_CHWR
I am a little bit confused. My understanding is that Trnsys performs the
calculation in the equation proforma based on the input and the sequence of the
equations as typed in the proforma, and the system performance at each time step
is determined component by component which follow the order as indicated in the
input file. Hence, should there be any improper formulation, the consequence
should generally be non-convergence. Is my interpretation wrong, and how can I
solve the problem? Please advise. Thank you!
Best Regards
LEE, Chun Kwong
City University of Hong Knog
---------- 已转发邮件 ---------- From: David BRADLEY <d.bradley@tess-inc.com>
To: a8304506@graduate.hku.hk Date: Tue, 14 Dec 2010 16:00:41 -0600 Subject: Re: [TRNSYS-users] Strange error when using the equation proforma
Chun Kwong, You are correct in your understanding of how TRNSYS iterates to solve. However, it has to have somewhere to start so TRNSYS performs a check on all the equations before starting the simulation to make sure that it can solve them. If you wrote a set of equations that said:
EQUATIONS 2 A = B B = A
there would be no way that TRNSYS could ever solve because it would have nowhere to begin the iteration. My guess is that your T_CHWS and T_CHWR equations are too interdependent and therefore can't be resolved.
Best, david
Hello, everyone.
I am trying to simulate a chiller plant with primary and secondary chilled water
pump systems. I use to equation proforma to calculate the chilled water flow
and temperature at the supply and return header. However, I get the following
error messages:
*** Fatal Error at time : 0.000000
Generated by Unit : Not applicable or not available
Generated by Type : Not applicable or not available
TRNSYS Message 420 : The following variable defined in an EQUATIONs or
CONSTANTs card could not be solved as this variable depends on either an
undefined EQUATION or CONSTANT name or depends on another EQUATION or CONSTANT
that cannot be solved. For example A=B and B=A would trigger this error
Reported information : T_CHWS
*** Fatal Error at time : 0.000000
Generated by Unit : Not applicable or not available
Generated by Type : Not applicable or not available
TRNSYS Message 420 : The following variable defined in an EQUATIONs or
CONSTANTs card could not be solved as this variable depends on either an
undefined EQUATION or CONSTANT name or depends on another EQUATION or CONSTANT
that cannot be solved. For example A=B and B=A would trigger this error
Reported information : T_CHWR
I am a little bit confused. My understanding is that Trnsys performs the
calculation in the equation proforma based on the input and the sequence of the
equations as typed in the proforma, and the system performance at each time step
is determined component by component which follow the order as indicated in the
input file. Hence, should there be any improper formulation, the consequence
should generally be non-convergence. Is my interpretation wrong, and how can I
solve the problem? Please advise. Thank you!
Best Regards
LEE, Chun Kwong
City University of Hong Knog
---------- 已转发邮件 ---------- From: David BRADLEY <d.bradley@tess-inc.com>
To: Catherine <xueyushuiyun@gmail.com> Date: Tue, 14 Dec 2010 16:18:17 -0600 Subject: Re: [TRNSYS-users] About building loads calculation in TRNSYS
Catherine, You are quite correct that integrating solar collectors with the building skin will change the loads on the building. I would guess that in simulating such a situation, most people ignore the interaction and assume that the presence of the collectors changes the loads only slightly in comparison to the magnitude of the loads themselves.
There are a few models of building-integrated photovoltaic panels in the TESS Green Building Library (now called the TESS Electrical Library) but they all assume an air gap behind the absorber surface and in front of the building skin.
Kind regards, David
On 12/9/2010 19:33, Catherine wrote:
I want to calculate the building loads when the flat-plate collector stick to the flat roof , but , how to achieve it using TRNSYS ? Well , I tend to utilize the Type 56 for building model .By the way , my building is an ordinary six-storey residential building .And there is no air gap between the collectors and the roof-covering . As well as collectors completely covered the flat roof , except the location for lacing the water tank .
On the one hand , since the collector block the radiation for the roof , which alters the energy balance of building , as well as causes changes in building loads. On the other hand , for the original building , after the collector added to the roof, the thermal resistance increases , with the building heat through the roof decreasing .